Process for the continuous manufacture of liquid nitric esters



F. A. F. CRAWFORD 2,606,919 PROCESS FOR THE CONTINUOUS MANUFACTURE.

' 0F LIQUID NITRIC ESTERS 2 SHEETS-SHEET l Inventor FREDERICK A. F. CRAWFORD Original Filed Dec. 6, 1946 M MM Attorneys Aug. 12, 1952 F. A. F. CRAWFORD 2,606,919 PROCESS FOR THE commuous MANUFACTURE V -OF LIQUID NITRIC ESTERS 7 Original Filed Dec. e, 1946 2 SHEETSSHEET 2 Inventor FREDERICK A. F. CRAWFORD Attorneys 7 Patented Aug. 12,1952

UNITED STATES PROCESS FOR THE CONTINUOUS MANUFAC- TUBE OF LIQUID NITRIC ESTERS Frederick A. F. Crawford, Aylesbury, Glenageary,

Ireland, assignor to Imperial Chemical Indus-' tries Limited, a corporation of Great Britain v Original application December 6, 1946, Serial Now 714,626. Divided and this application June 28, I 1949, Serial No. 101,834. In Great Britain Dec'ember 7, 1945 2 Claims.

This invention relates to improved process for the continuous manufacture of explosive liquid nitric esters from rapidly esterifiable liquid polyhydric alcohols and especially to the continuous manufacture of nitroglycerine and the like. More particularly, the invention relates to a process provided with an improved circulatory means for the manufacture of the aforesaid explosive liquid nitric esters, wherein the esterifiable organic liquid compound is continuously nitrated with a nitrating acid medium and the resulting liquid nitric ester is separated from the refuse nitrated acid.

This application is a division of applicants application Serial No. 714,626, filed December 6, 1945, now U. S. Patent No. 2,579,474.

The object of this invention is to provide a suitable process which may be used with relative safety for the continuous production of liquid explosive nitric esters which includes means for quickly and continuously removing by centrifugal separation the liquid explosive nitric ester from a continuous succession of relatively small quantitles of a mixture of said liquid explosive nitric ester and refuse nitratin'g acid resulting from the interaction of a liquid polyhydric alcohol and nitrating acid.

Other objects and details of the invention will become apparent from the following description when read in connection with the accompanying drawings wherein:

Figure 1 is a vertical section of the general arrangement of apparatus used in this invention, and

Figure 2 is an enlarged vertical section of the mixing vessel forming part of the apparatus.

According to this invention, the process for the continuous manufacture of explosive liquid nitric esters from rapidly esterifiable liquid polyhydric alcohols, comprises continuously introducing the alcohol and nitrating acid into a mixing space, subjecting the incipiently reacted mixture to continuous circulation by impelling itat a rate suflicient to maintain turbulence throughout the circulation out of the lower part of said space through a narrow externally cooled tubular conduit external to said space to a horizontally remote locus at which the reaction is complete and back into the upper part of said space, bleeding off a portion of the substantially completely reacted mixture at said remote locus, and separating by continuous centrifugal action the liquid explosive nitric ester from the bled off portion while the latter is still in emulsion form.

Preferably, the resulting continuously sepa- (Cl. Edd-467) rated liquid explosive nitric ester is immediately emulsified with an aqueous washing medium.

As long as the liquid explosive nitric ester remains emulsified in the refuse nitrating acid in its passage between the nitrating vessel and the centrifugal separator, there is no danger of any detonation, arising in the centrifugal separator being carried back through the column of liquid to the nitrator. The proviso according to-the present invention that theincipiently reacted mixture is to be impelled at a rate sufficient to maintain turbulence throughout the circulation of the reaction mixture past a horizontally remote locus makes it possible for the nitrating vessel and the centrifuge to be sufiiciently distanced so that no explosion debris from either is likely to reach the other.-

Apparatus suitable for the process set forth supra comprises a mixing vessel having a lower portion of larger diameter accommodating a rotary impeller and an upper neck portion of smaller diameter open at the top accommodating the shaft of the said impeller, inlets for the liquid reagents, an external circulation pipe jacketed over substantially its whole length and leading from the vessel at the level of the impeller to a horizontally remote locus and returning into the neck of said vessel, a continuous centrifugal separator in the vicinity of said locus at a lower hydrostatic level than said vessel and a branch communication from a portion of said external circulation pipe at said locus entering said centrifugal separator. The separator is provided with an outlet for the refuse acid and an outlet for the separated liquid explosive nitric ester which leads to re-emulsifying apparatus in which said ester is emulsified in an aqueous Washing liquid in close proximity to the separator. The centrifugal separator and the re-emulsifying apparatus are preferably shielded by a surrounding bafile structure, and a baflle structure is preferably interposed between the mixing vessel and the remote part of the circulating pipe. The external circulating pipe passes through the latter. valve. Also, the impeller shaft of the mixing vessel may be provided, if desired, with stirrer blades.

Referring to Figures 1 and 2 of the accompanying drawings, a mixing vessel I is provided with a rotating impeller 2, an outlet 3 at the level of the impeller provided with a jacketed covering, and a return or inlet portion 4. The jacketed outlet 3 extends horizontally to a remote locus such as that locus designated by the numeral 3' and then returns horizontally in con- Pipe 8 is a refuse acid outfiow pipe and His an emergency run-away cock. A concret'e lined.

trench 10 provided with a concrete explosion bafiie ll running transversely across the trench' either of the vessels reaching the other-vessel.-

An overflow gutter l8 and a'concrete shielding structure l2 are provided for the centrifugal separator 6 for reasons explained hereinafter.

As best seen in Figure 2, outer walls of the jackets 3a-and qa are provided aboutpipes 3. and 4, respectively and thus provide a means for cooling the circulated reaction mixture. Inlet pipes Band 14 are provided for theliduidpolyhydric alcohol andthe nitr ating'acid, respectively. Bottom I l,- forming.the bottomplosure for the mixing vessel I,- may be destroyed by means not shown if an emergency should arise requiring that the contents-of the mixingvessel :be emptied into thetrench l0. V

Theinvention has the. advantage that no mat ter how far distant is the locus; from which the streamis bled off to the separator, the whole stream circulating from the mixing vessel to said locus and back again is'maintained in emulsion by its turbulent flow.- As the distance the emulsion has to travel from'said-lo-cus to the separator, over which itis riot-inaintainecl in turbulent flow by theim-pelling-me ans'may be madeveryshort, it-followsthat the horizontal distance between i the separator and: the mixing vessel may be made very considerable without any separation of theemulsion'travelling between the two;vessels-taking placejand hence without the possibility of a detonation in one of 45 the. vessels beings communicated throughf the liquid to the other. Moreover, the separator and the mixing vessel may be so positioned that should a detonation occur in one of these, its force will not be sufficient to injure the operator situated beside the other.

The description of the process of'this invention and the apparatus used therefor is for the purpose of illustration only and is not of limitation;

1. A process for the continuous manufacture of explosive liquid nitric esters from rapidly esterifiable liquid polyhydric alcohols which comprises continuously introducing the alcohol and nitrat- 15 mg acid into a mixing zone, subjecting the incipiently reactedmixture to continuous circulation by-iinpellingit; at a rate sufiicient to maintain turbulence throughout the circulation, from the lower part of said zone to a horizontally remote locus at which thereaction is complete and backinto the upperpart of said zone, bleeding oifa portion ofthe completel-yreacted mixture at said remote locus; and separating by: continuous centrifugalaction the liquid 'explosivenitric ester from the bled off portion-while the latter isstill in emulsion form,-

2. A process as-set forth in claim Lwherein the resulting continuously separated liquid ex-- plosive nitric ester is immediately-- emulsified with an aqueous washing medium;

F. A: F. CRAWFORD REFERENCES CITED- The following referencesvarei of: record iri the file of thispatent:v

UNITED STATESPATENTS' FOREIGN PATENTS Number Country" 7 Date 383821 Sweden; Apr. 22, 1913 

1. A PROCESS FOR THE CONTINUOUS MANUFACTURE OF EXPLOSIVE LIQUID NITRIC ESTERS FROM RAPIDLY ESTERIFIABLE LIQUID POLYHYDRIC ALCOHOLS WHICH COMPRISES CONTINUOUSLY INTRODUCING THE ALCOHOL AND NITRATING ACID INTO A MIXING ZONE, SUBJECTING THE INCIPIENTLY REACTED MIXTURE TO CONTINUOUS CIRCULATION BY IMPELLING IT, AT A RATE TO CONTINUOUS CIRCULATAIN TURBULENCE THROUGHOUT THE CIRCULATION, FROM THE LOWER PART OF SAID ZONE TO A HORIZONTALLY REMOTE LOCUS AT WHICH THE REACTION IS COMPLETE AND BACK INTO THE UPPER PART OF SAID ZONE, BLEEDING OFF A PORTION OF THE COMPLETELY REACTED MIXTURE AT SAID REMOTE LOCUS, AND SEPARATING BY CONTINUOUS CENTRIFUGAL ACTION THE LIQUID EXPLOSIVE NITRIC ESTER FROM THE BLED OFF PORTION WHILE THE LATTER IS STILL IN EMULSION FORM. 